Switch



May 1, 1934;

D. G. TAYLOR Filed April 13, 1952 SWITCH 2 Sheets-Sheet l "{IJVENTOR Daniel G. Taylor,

TTORNEYS Filed April 15. 1953 2 Sheets-Sheet 2 INVENTORI I Daniel (7. Ta 5102', W 35%.

ATTORNEYS Patented May 1, 1934 1 "UNITED STATES PATENT OFFICE swrron Application April 13, 1932, Serial No. 605,106

3 Claims.

The object of my invention is to provide an apparatus by means of which an element, such, for instance, as a damper controlling lever, may be variably positioned, throughout its entire range 5 of movement, in response to variations of temperature at a predetermined point.

More specifically the object of my invention is to provide a snap-action circuit-controlling structure, in combination with mechanism of the above-described character, whereby accurate and sensitive responsive action of the mechanism may be insured through a long period of time without expert supervision.

The accompanying drawings illustrate embodiments of my invention.

Fig. 1 is a diagrammatic illustration of one form,

Fig. 2 is a similar diagram of another form, and

Fig. 3 a diagrammatic side elevation, on a larger 20 scale, of the snap switch mechanism.

In the drawings indicates a heat-responsive bellows, of well known form, which forms the power delivery element of theapparatus. This bellows, or other suitable expansible and contractible element, is mounted on a suitable base so that one of its end walls 11 may move back and forth in response to variations in pressure within the bellows. Communicating with the interior of the bellows 10, through a small tube 12, is a capsule 13, and bellows, tube and capsule are filled with a medium preferably quickly and considerably responsive to temperature variations, conveniently a volatile liquid such as SO2CzH5-OC2H5, etc.

Carried by the end wall 11 is a stem 14 which is connected to a lever 15 which, in turn, may.

be connected to the draft and check dampers (not shown) of a househeating furnace.

A contact-controlling arm is supported upon the free ends of two bi-metallic thermostatic blades 21 and 22 so that its free end may be swung back and forth in response to the variable positioning of the free ends of blades 21 and 22 in response to variable heating of said blades.

Arranged to respectively heat blades 21 and 22, are electric heater coils 23 and 24 connected by wires 25 in series with the resistance coil 26 of a thermostat S of the potentiometer type. The heat-responsive (preferably bi-metallic) blade 2'7 of thermostat S sweeps coil 26 and is connected by wire 28 with one end of the secondary 29 of a step-down transformer T.

The other end of the secondary 29 is connected by wire 30 to the junction 31 between heater coils 23 and 24. r

Arranged so as to heat capsule 13 is an electric heater coil 35- one end of which is connected by wire 36 to wire 28 between blade 27 and coil 29, 61) and the other end of which is connected, through separable terminals responsive to variable positioning of arm 20, to the other end of coil 29.

The high tension primary coil 40 of transformer T is connected by leads 41 and 42 to suitable energizing line wires so that there is a continuous flow of current through the secondary circuit 29, 28, 2'7, 26, 25, 23, 24, the coils 23 and 24 being continuously proportionally heated in accordance with the position assumed by blade 27 on coil 26 (0 in response to the temperature of the medium surrounding blade 27.

The mechanism thus far described'is not original with me and in prior devices of this character contacting of separable terminals in the energizing circuit of heater 35 has been dependent upon coordinated movements of stem 14 and arm 20 but the contacting and separation of such terminals has not been sumciently uniform and positive to avoid serious and objectionable deteriora- 30 tion of the contact points and non-uniformity of operation.

In the present construction a plate 50 of insulating materialis secured to stem 14 so as to be moved thereby. Mounted on this plate is a 35 I pivoted at 56 on plate 50. Lever 55 is biased toward stop 57 by a spring 58.

Pivoted at 60, on plate 50, is a latch 61 having a finger 62 cooperative 'with the free end of spring finger. 54 to hold terminal 53 either in engagement with, or out of engagement of, terminal 51, and this latch is biased away from finger 54 by a spring 63.

Latch 61 is provided with a cam 64 which may be overridden by a finger 55" carried by lever 55.

Arranged adjacent lever 55, so as to obstruct its downward movement with stem 14, is a cam 70 which is connected with arm 20 so as to be positioned thereby, and this cam is slidably supported by a guideway 71.

Terminal 53, through finger 54, is electrically connected to one end of heater coil 35 by wire 72.

Assuming the various parts to be in the positions shown in the drawings, the energizing circuit of heater 35 is broken at 51-53 and the content of bellows 10, tube 12 and capsule 13 is contracting so that stem 14 is moving downwardly.

Heaters 23 and 24 are affecting their respective blades 21 and 22 thereby causing element 20 to position cam at a particular point relative to lever 55 determined by the position of blade 27 on coil 26. As stem 14 moves downwardly lever 55 contacts with cam 70 and the lever will be swung against its bias (to the right in the diagram) and finger 55 will ride over cam 64 to first project finger 62 into obstructing position in front of spring finger 54, thus preventing terminal 53 from being swunginto contact with terminal 51 as stem 14 descends and lever 55 swings to the right.

As the descent of stem 14 continues, finger 55' passes beyond cam 64 so that spring 63 retracts finger 62 from the stressed spring finger 54 and thus permits said spring finger to suddenly close terminal 53 upon terminal 51 to close the circuit 29, 30, 52, 51, 53, 54, '72, 35, 36, 28.

Heater 35 is thus energized so as to heat the capsule l3 and bellows 10begins promptly to expand and move stem 14 upwardly. The upward movement of stem 14 permits spring 58 to draw lever 55 to-the left whereupon finger 55', riding to the left over cam 64, projects finger 62 down back of finger 54 thereby holding terminal 53 in contact with terminal 51 until finger 55 passes beyond cam 64, whereupon spring finger 54 is released and quickly separates terminal 53 from terminal 51. w

It will be noted that the above described construction insures a definite contacting of terminals 51 and 53, during a definite interval; that the force required to move terminal 53 into and out of contact with its fellow 51 is developed by the relatively strong motor element 10; and that, except when lever 55 is actually in contact with cam '70, said cam is entirely free to bemodulated as to its position by the conjoint action of blades 21 and 22 on arm 20.

Cam '70 may be very light and may move easily over its supporting guideway 71 so that very light and extremely sensitive thermostatic blades 21 and 22 will be amply sufllcient to furnish the necessary power for this purpose although they would not be suflicient to insure proper and effective contact between the terminals 53 and 51.

The amount of movement of stem 14 requisite to produce the snap action of finger 54 will, of course, be dependent upon the proportions of the cooperative parts but any competent designer will readily be 'able to so proportion the parts that any desired or a very slight movement of the stem 14 will be necessary to produce the desired snap action.

So long as cam 70 remains in any one position of adjustment heater 35 will be regularly energized and de-energized and stem 14 will with regularity float up and down through the short range of movement required to produce the snap action. Adjustment of cam '70 will momentarily vary the regularity which stem 14 modulates to its new but equal range of movement as determined by the current position of blade 27 rela omitted) is a comparatively gradual process and consequently the responsive movement of stem 14, at least the beginning of movement in either direction, is -camparatively slow so that, if coordination of terminals 51 and 53 were di ect y dependent upon movement of stem 14, as has been the case in some prior structures, the tendency to sparking and inefilcient energization of the heater 35 is considerable and materially detracts from accuracy of operation.

In the present construction quick and definite co-ordination of the terminals 51-53 insures proper making and breaking of the circuit of heater 35 and intervals of heatingare all uniform except as single intervals are occasionally lengthened or shortened as a result of, repositioning of cam '70.

In practice the thermal inertia of the bellows 10, tube12 and capsule 13 is such that plate 50 will rise slightly after heater 35 has been de-' energized so that lever 55 will be lifted from cam 70 thus freeing said cam so that it may be moved by a comparatively small force. The blades 21 and 22 may thus be very light and will consequently be very sensitively responsive to variations in the heating effects of their respective heaters 22 and 24.

It will, of course, be understood that the energizing circuits might be" directly connected to commercial circuits or that the heater 35 might be separately energized from commercial lines, as indicated in Fig. 2, where the circuit 42, 300, 52, 51, 53, 54, 720, 35, 360, 41 takes the place of circuit 29, 30, 52, 51, 53, 54, '72, 35, 36, 28 in Fig. 1. In that case wire 30 proceeds directly from 29 to 31 without connection with 52.

I claim as my invention:

1. A snap switch comprising a main body, a terminal carried thereby, a cooperating spring terminal, a carrier for said spring terminal movably mounted on said main body to shift the spring terminal toward or from its fellow, a latch movable into and out of position to restrain movement of the spring terminal in response to movement of said carrier, and interengaging means carried by the latch and carrier to produce movement of said latch into and out of obstructing position as a result of carrier movement.

2. A snap switch comprising a main body, a terminal carried thereby, a cooperating spring terminal, a carrier for said spring terminal movably mounted on said main body to shift the spring terminal toward orfrom its fellow, a latch movable into and out of position to restrain movement of the spring terminal in response to initial movement of saidcarrier, interengaging means carried by the latch and carrier to produce movement of said latch into and out of obstructing movement as a result of carrier movement, an actuator for said carrier, and means for producing relative movement between the carrier and actuator to cause movement of the carrier to stress the spring terminal.

3. A snap switch comprising a main body, a terminal carried thereby a cooperating spring terminal, a carrier for said spring-terminal movably mounted on said main body to shift the spring terminal toward or from its fellow, a latch movable into and out of position to restrain movement of the spring terminal in response to initial movement of said carrier, interengaging means carried by the latch and carrier to produce movement of said latch into and out of obstructing movement as a result of carrier movement, a variably positionable actuator for said carrier, and means for producing relative movement between the carrier and actuator to cause movement of the carrier to stress the spring terminal.

DANIEL G. TAYLOR. 

